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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 575-578 (Apr. 2008), p. 1314-1319 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Asphalt pavement serving as solar collector has been developed for the heating and coolingof adjacent buildings as well as to keep the pavement ice-free directly. Material parameters such asthermal conductivity and heat capacity are some of the critical parameters related to the efficiency ofthe asphalt collector. Graphite powders were utilized as thermal conductive fillers to make asphaltcollector conductive so as to improve the efficiency of the asphalt collector. The material parameterschange with the addition of graphite consequently. In order to access the solar energy absorbability ofconductive asphalt collector, it is necessary to predict the temperature distribution within the asphaltlayers. A transient, two-dimensional finite element model is developed to predict temperaturedistributions in conductive asphalt solar collector due to material parameters. The ability of accuratelypredict asphalt pavement temperature at different depths will greatly help pavement engineers indetermining the solar energy potential of conductive asphalt collector. The results from the predictionmodel show that the surface temperature of pavement decreases slightly with addition of graphite.The differential maximum asphalt temperature variation at a depth of 10cm is significantly more thanthat at the surface. Higher temperature and lower temperature gradient can also be observed at thedepth of 10cm because the heat conduction is accelerated by the addition of graphite
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1524-475X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Diabetes-induced impaired wound healing is characterized by inhibition of the inflammatory response to wounding, macrophage infiltration, angiogenesis, fibroplasia, reparative collagen accumulation, and wound breaking strength. Because all of these processes are accelerated in normal rats by a single local application at operation of Staphylococcus aureus peptidoglycan, we hypothesized that S. aureus peptidoglycan would prevent diabetes-induced impaired wound healing, despite persistent, untreated hyperglycemia, polydipsia, glycosuria, and polyuria. Sprague-Dawley male rats were divided into two groups. One group received an intraperitoneal injection of streptozotocin (65 mg/kg) in citrate solution; the other group received an intraperitoneal injection of an equivalent volume of citrate solution. Seventeen days after the injections, the diabetic and control rats received aseptically two 5.5-cm paravertebral incisions and subcutaneous implantation of six polyvinyl alcohol sponges, three on each side. On one side, each sponge contained 0.5 mg S. aureus peptidoglycan in 50 µl saline solution, and the incision was inoculated along its length with 4.7 mg S. aureus peptidoglycan in 157 µl saline solution (860 µg/S. aureus peptidoglycan/cm incision); on the other side, the same respective volumes of saline were used. During the preoperative and postoperative periods, diabetic rats lost a small amount of weight (2%), were hyperglycemic (363 ± 10 mg/100 ml blood), polydipsic, glycosuric, and polyuric, whereas the controls gained weight (25%) and were normoglycemic (104 ± 5 mg/100 ml blood); these differences were significantly different (p 〈 .001 in each case). In controls, S. aureus peptidoglycan inoculation increased wound breaking strength (by a factor of 2.0) and hydroxyproline content (by a factor of 1.4; p 〈 .001 in each case); in diabetics, there were significant decreases in wound breaking strength (by a factor of 1.7) and hydroxyproline content (by a factor of 1.3) of saline solution-inoculated incisions and sponges compared with the wound breaking strength and hydroxyproline content of saline solution-inoculated incisions and sponges in controls (p 〈 .02 and p 〈 .001, respectively). These decreases were completely prevented when the incisions and polyvinyl alcohol sponges had been inoculated at operation with S. aureus peptidoglycan; S. aureus peptidoglycan inoculation in the diabetic rats increased wound breaking strength by a factor of 2.2 and sponge reparative tissue hydroxyproline by a factor of 1.6 (p 〈 .001 in each case). Thus, diabetes-induced impaired wound healing was prevented completely by a single local instillation at operation of S. aureus peptidoglycan, despite persistent, untreated hyperglycemia, polydipsia, polyuria, and glycosuria.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 348-349 (Sept. 2007), p. 145-148 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: It is currently interesting to use thermal or electrical conductive asphalt concretefor snow-melting and maintenance of asphalt pavements in winter. The addition of conductivefillers may have negative effects on the mechanical properties of asphalt concrete. Theperformance of conductive asphalt concrete is greatly affected by the initial crack and itspropagation. Laboratory tests for neat and conductive asphalt concrete include DynamicModulus Test (DMT) and Indirect Tensile Fatigue Test (ITFT). DMT tests indicates that thevalue of dynamic modulus of asphalt concrete decreases with the increasing graphite content.It means that the conductive asphalt concrete achieves lower stiffness. It can be concludedfrom ITFT tests that the fatigue life (load cycle times) of conductive asphalt concrete is morethan neat ones when stress level is under 1.0 MPa. Meanwhile higher fatigue resistance ofconductive asphalt concrete is observed when carbon fibers (2 weight % of total aggregate)were added together with 22% graphite, especially at low stress levels
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 348-349 (Sept. 2007), p. 885-888 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Recycled asphalt mixture is a multiphase system, which consists of sized recycled asphaltpavement (RAP), new asphalt, and/or recycling agents and new aggregates. RAP percentages mayhave influences on performance of total recycled asphalt mixture. The performance of asphalt mixtureis significantly affected by its dynamic response and fatigue performance (crack formation andpropagation). Dynamic and fatigue properties of virgin and recycled asphalt mixture are investigatedbased on Indirect Tensile Test (ITT). It is demonstrated in test results that recycled asphalt mixture isstiffer and more elastic-like than virgin ones with RAP added. The number of load cycles to fatiguefailure expected of recycled asphalt mixture is a bit decrease compared with that of virgin ones in lowstress level. In addition, high fatigue resistance of recycled asphalt mixture is observed in this testwhen stress level is high
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 33 (1998), S. 1233-1237 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Silicon carbide (SiC) and aluminium nitride (AlN) were found to form a solid solution at temperatures above 1800°C. Based on this interesting result, the composite was fabricated by mechanical mixing of the SiC and AlN powders, and hot pressed under 40 MPa at 1950°C in an argon atmosphere. The objective was to achieve full density and minimize solid solution formation. During the sintering process, the SiC–AlN system passed through three steps to form the solid solution at the end. First, the AlN particle is vaporized from its surface; next, the evaporated AlN is deposited on the surface of the SiC grains and the AlN particle, accompanied by a reduction in its size, and finally, partial SiC and AlN solid-solution formation on the boundary of the SiC grains. Because of the AlN deposition and solid-solution formation at the boundary of SiC grains, a barrier layer was present on the surface of SiC grains. This leads to the formation of fine grains. The toughening mechanism is thought to be by thermal residual stresses, due to the difference between the coefficients of thermal expansion of the matrix SiC and that of the dispersed AlN particles, and crack deflection around the SiC grains. Therefore, it is that which improves the mechanical properties of the SiC–AlN composite. © 1998 Chapman & Hall
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The constitution of glasses in the systems M2O3-TeO2 (M = B and In) was investigated by Raman and infrared spectroscopy. From the relation between the M2O3 content and the intensity ratios of the deconvoluted Raman peaks I(720)/I(665) and I(780)/I(665), it was concluded that In2O3 behaves as a network modifier to yield TeO 3 − units and that discrete BO3 and BO4 units construct a network of glasses containing boron oxide. A structural model for those glasses was derived which involves three-coordinated oxygen atoms and TeO4 units of an intermediate configuration, O3Teδ+ ...Oδ-.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plasma chemistry and plasma processing 11 (1991), S. 151-168 
    ISSN: 1572-8986
    Keywords: Drag force on a sphere ; thermal plasma flow ; experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Experimental data are presented concerning the drag force on a stationary phere exposed to an argon plasma flow with temperatures about 104 K and velocities about 102 m/s. A novel probe construction has been employed in the drag measurements in order to exclude the effect of the supporting wire on the sphere drag data. By using the new probe construction with a compensating wire, drag forces on an individual steel sphere in the plasma flow have been measured and compared with those obtained by using the probe construction ernployed by a few previous authors. Experimental results show that the measured drag forces are always less than their counterparts obtained from the standard sphere-drag curve under isothermal flow conditions with the same Reynolds numbers based on the oncoming plasma properties. The drag force on a sphere increases only slightly with the increasing surface temperature of the sphere before it melts. Appreciable diference was found between the experimental data and the predicted results of the available expressions for drag on a sphere exposed to a thermal plasma flow. Further research effort is required to build a more suitable drag correlation.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 48 (1997), S. 169-180 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0887-624X
    Keywords: N-(4-N′, N′-dimethylaminophenyl)maleimide ; fluoroescence structural self-quenching effect ; initiation ; polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A maleimide bearing electron-donating chromophore, N-(4-N′,N′-dimethylaminophenyl)-maleimide (DMAPMI) was synthesized from N, N-dimethylaminoaniline and maleic anhydride in the presence of acetic anhydride and sodium acetate. DMAPMI can be easily copolymerized with vinyl acetate (VAc). In addition, it can be easily homopolymerized by UV light irradiation or by using AIBN or BPO as an initiator. The fluorescence spectra of DMAPMI and its polymer or copolymer were recorded and compared at the same chromophore concentrations. It was observed that the fluorescence emission intensity of DMAPMI was much lower than those of its polymers. This may be due to the occurrence of intermolecular charge transfer interaction between the electron-donating dimethylaminophenyl moiety and acrylic electron-accepting carbon-carbon double bond in the monomer. The model compound, N-(4-N′, N′-dimethylaminophenyl)succinimide (DMAPSI), which has no carbon-carbon double bond, displayed the same fluorescence behavior as DMAPMI polymers. The fluorescence of DMAPMI polymers and DMAPSI can be quenched by electron-deficient compounds such as AN, TCNE, MMA, etc. All these results supported the above conclusion. This is another example of the “fluorescence structural self-quenching effect” termed by us previously and demonstrates again that this phenomenon is not an accidental but a general one for acrylic monomers bearing electron-donating chromophores. Study of the initiation behavior of DMAPMI and its polymer showed that they could initiate the photopolymerization of AN, by combination with BPO, they could also initiate the thermopolymerization of vinyl monomers such as MMA. © 1996 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 26-34 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A set of 4-monosubstituted cyclopentenes, , were synthesized and their relative rates (kX/kH) for bromination and chlorination were determined in methanol, ethanol and acetic acid at 25 °C by competitive method. log(kX/kH) for most of the substituents can be correlated by means of Taft's equation, log(kX/kH) = ρI σI + C. In methanol ρI, Br2 = -2·91, ρI, Cl2 = -0·49, in ethanol ρI, Br2 = -3·07, ρI, Cl2 = -0·70 and in acetic acid ρI, Br2 = -1·64, ρI, Cl2 = -0·65. The presence of C(〈0) is due to a constant steric effect. The deviation of X = H is ascribed to the absence of the steric effect and that of X = CO2Me and CO2Et is accounted for in terms of anchimeric assistance. For chlorination no anchimeric assistance was observed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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